New Delhi/Patna, Oct. 11: A laboratory contamination of a suspected stool sample from a patient in Darbhanga district triggered a false alarm of polio in Bihar until a Mumbai laboratory ruled it out this evening.
The Union health ministry said this afternoon that a suspected case of wild poliovirus type-3 from Darbhanga was under investigation and the Bihar government was preparing to launch an immunisation drive in several districts.
But a senior state health official and the National Polio Surveillance Project said that confirmatory studies on the sample have ruled out polio.
Bihar health secretary Sanjay Kumar said the investigation had first shown a positive result due to contamination in a Lucknow laboratory where the test was conducted on Wednesday night.
“The stool sample of the suspected patient was sent to a lab in Lucknow. There they keep polio virus samples to match them with samples collected from suspected patients. In the first result, the stool somehow got contaminated with P3 strain of the virus and the result came positive. However, the test carried out today confirmed that it was not a polio case,” he said.
The sample was that of a child from Manigachi block in Darbhanga district, around 180km northeast of Patna, whose stool sample was sent for test after symptoms of Acute Flaccid Paralysis (AFP) was found in the child. AFP is different from polio in the sense that most non-polio AFP patients get back strength in the affected leg after treatment.
India’s last documented case of polio was a child from Howrah in Bengal in January 2011. Earlier this year, India celebrated a full year free of polio. A country has to remain free of polio for three years to be certified as having eradicated it. The type-3 wild poliovirus is currently prevalent in Nigeria and Pakistan.
Earlier, in a hastily called meeting by senior health department officials in Patna, the state had decided to launch an intensive immunisation drive in the northern part of the state beginning Monday.
“Even though the suspected case has turned out to be a negative one we have decided to launch a special drive of polio drop administration in all north Bihar districts from October 15 as a precautionary measure,” principal secretary, health, Vyasji said.
Hemant Shukla, regional team leader of WHO’s National Polio Surveillance Project, said the Bihar government has chalked out an elaborate plan in case of any detection of polio transmission.
A medical virologist told The Telegraph that any abrupt emergence of wild poliovirus would be a surprise and a setback. “There has been no sign of wild poliovirus in sewage water samples from Delhi, Mumbai, Patna, Calcutta and elsewhere,” the virologist said.
Sewage water has long been used by the polio surveillance network laboratories as a proxy indicator for circulating polio viruses.